Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A23A28

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N24224 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A23A28
Octal
50435050
Decimal
10,631,720
Country
US
Tail
N24224
Type
B738
No current signal · last broadcast Jul 26, 22:00 UTC
Flights observed
477
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:00 UTC

Last known position

Most recent position reported by Mode-S A23A28.

Country allocation

The ICAO 24-bit address A23A28 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 20 distinct

Callsign Airline Flights Last seen
UAL478 - 5 2026-07-21
UAL1919 - 5 2026-07-07
UAL1601 - 5 2026-07-10
UAL1278 United Airlines 5 2026-05-07
UAL618 - 4 2026-07-02
UAL362 United Airlines 4 2026-06-13
UAL275 United Airlines 4 2026-07-25
UAL251 United Airlines 4 2026-06-15
UAL2484 - 4 2026-04-18
UAL2350 United Airlines 4 2026-07-17
UAL1787 United Airlines 4 2026-06-06
UAL1625 United Airlines 4 2026-05-03
UAL1381 - 4 2026-06-15
UAL719 United Airlines 3 2026-06-06
UAL703 - 3 2026-07-21
UAL669 United Airlines 3 2026-05-18
UAL623 United Airlines 3 2026-05-11
UAL525 United Airlines 3 2026-07-26
UAL490 United Airlines 3 2026-05-30
UAL318 - 3 2026-07-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL298 AUS → EWR Jul 26, 20:15 UTCJul 26, 22:00 UTC1h 45m
2026-07-26 UAL213 SFO → EWR Jul 26, 17:05 UTCJul 26, 18:20 UTC1h 15m
2026-07-26 UAL525 IAD → AMM Jul 26, 12:35 UTCJul 26, 15:30 UTC2h 55m
2026-07-26 UAL2674 BNA → EWR Jul 26, 02:50 UTCJul 26, 03:15 UTC25m
2026-07-26 UAL2674 BNA → EWR Jul 26, 02:56 UTCJul 26, 03:16 UTC20m
2026-07-26 UAL1911 IAD → EWR Jul 26, 00:30 UTCJul 26, 01:10 UTC40m
2026-07-25 UAL1911 IAD → EWR Jul 25, 22:45 UTCJul 25, 22:55 UTC10m
2026-07-25 UAL275 EWR → SFO Jul 25, 21:05 UTCJul 25, 21:20 UTC15m
2026-07-25 UAL275 EWR → SFO Jul 25, 19:00 UTCJul 25, 19:25 UTC25m
2026-07-25 UAL2141 PHX → SFO Jul 25, 16:05 UTCJul 25, 17:20 UTC1h 15m
2026-07-25 UAL2141 PHX → SFO Jul 25, 15:31 UTCJul 25, 17:16 UTC1h 45m
2026-07-25 UAL3909 BRU → IAD Jul 25, 12:15 UTCJul 25, 13:15 UTC1h 0m
2026-07-25 UAL3909 BRU → IAD Jul 25, 12:19 UTCJul 25, 14:09 UTC1h 50m
2026-07-25 UAL1986 RDM → SFO Jul 25, 03:20 UTCJul 25, 05:50 UTC2h 30m
2026-07-24 UAL2388 LAS → EWR Jul 24, 22:00 UTCJul 25, 00:45 UTC2h 45m
2026-07-24 UAL2388 LAS → EWR Jul 24, 22:01 UTCJul 25, 00:40 UTC2h 39m
2026-07-24 UAL1535 EWR → ORD Jul 24, 17:15 UTCJul 24, 19:45 UTC2h 30m
2026-07-24 UAL525 AUS → IAD Jul 24, 12:44 UTCJul 24, 15:36 UTC2h 52m
2026-07-24 UAL525 AUS → IAD Jul 24, 12:40 UTCJul 24, 15:35 UTC2h 55m
2026-07-24 UAL2332 SFO → MCO Jul 24, 05:15 UTCJul 24, 05:40 UTC25m
2026-07-24 UAL2332 SFO → MCO Jul 24, 01:15 UTCJul 24, 04:30 UTC3h 15m
2026-07-23 UAL2823 IAD → EWR Jul 23, 22:50 UTCJul 23, 23:55 UTC1h 5m
2026-07-23 UAL571 AUS → SFO Jul 23, 19:25 UTCJul 23, 20:30 UTC1h 5m
2026-07-23 UAL571 AUS → SFO Jul 23, 19:22 UTCJul 23, 20:28 UTC1h 6m
2026-07-23 UAL520 - Jul 23, 16:35 UTCJul 23, 17:30 UTC55m
2026-07-23 UAL2127 LGA → ORD Jul 23, 13:15 UTCJul 23, 14:15 UTC1h 0m
2026-07-23 UAL8267 YHZ → YYZ Jul 23, 08:11 UTCJul 23, 08:54 UTC43m
2026-07-23 UAL8267 YHZ → YYZ Jul 23, 07:55 UTCJul 23, 09:00 UTC1h 5m
2026-07-23 UAL2338 PSP → SFO Jul 23, 05:40 UTCJul 23, 07:05 UTC1h 25m
2026-07-23 UAL1843 SFO → ORD Jul 23, 02:20 UTCJul 23, 04:00 UTC1h 40m
2026-07-22 UAL1294 DEN → YEG Jul 22, 18:00 UTCJul 22, 19:40 UTC1h 40m
2026-07-22 UAL2853 DEN → EWR Jul 22, 14:05 UTCJul 22, 15:50 UTC1h 45m
2026-07-22 UAL2819 DEN → SAT Jul 22, 00:35 UTCJul 22, 02:15 UTC1h 40m
2026-07-21 UAL478 - Jul 21, 20:35 UTCJul 21, 21:40 UTC1h 5m
2026-07-21 UAL478 BIL → DEN Jul 21, 20:42 UTCJul 21, 21:38 UTC56m
2026-07-21 UAL703 - Jul 21, 18:00 UTCJul 21, 19:00 UTC1h 0m
2026-07-21 UAL2459 STL → DEN Jul 21, 14:30 UTCJul 21, 16:20 UTC1h 50m
2026-07-21 UAL214 HNL → SFO Jul 21, 03:35 UTCJul 21, 05:05 UTC1h 30m
2026-07-20 UAL1236 EWR → PHX Jul 20, 22:55 UTCJul 21, 01:15 UTC2h 19m
2026-07-20 UAL1767 DEN → DCA Jul 20, 18:26 UTCJul 20, 20:45 UTC2h 19m
2026-07-20 UAL1767 DEN → DCA Jul 20, 18:20 UTCJul 20, 20:50 UTC2h 30m
2026-07-20 UAL1727 LAS → SFO Jul 20, 13:25 UTCJul 20, 16:25 UTC3h 0m
2026-07-20 UAL248 BOS → IAH Jul 20, 00:10 UTCJul 20, 02:50 UTC2h 40m
2026-07-19 UAL2155 - Jul 19, 21:45 UTCJul 19, 22:40 UTC55m
2026-07-19 UAL2383 PHL → DEN Jul 19, 19:10 UTCJul 19, 19:55 UTC45m
2026-07-19 UAL348 DEN → DEN Jul 19, 14:00 UTCJul 19, 17:55 UTC3h 55m
2026-07-19 UAL1269 YYC → DEN Jul 19, 01:32 UTCJul 19, 03:16 UTC1h 44m
2026-07-19 UAL1269 YYC → DEN Jul 19, 01:25 UTCJul 19, 03:20 UTC1h 55m
2026-07-18 UAL2232 DEN → YYC Jul 18, 22:00 UTCJul 19, 00:00 UTC2h 0m
2026-07-18 UAL1195 - Jul 18, 19:25 UTCJul 18, 20:35 UTC1h 10m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the N24224 page for operator, model, and routing details .

Mode-S A23A28 frequently asked

What is Mode-S code A23A28?
A23A28 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N24224.
Where is Mode-S A23A28 registered?
Mode-S code A23A28 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A23A28 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:00 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A23A28, octal 50435050, decimal 10,631,720.
What flights does A23A28 operate?
Mode-S A23A28 has broadcast 20 distinct callsigns, including UAL478, UAL1919, UAL1601, UAL1278, UAL618.